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By Eugene E. Brucker

In recent years, there has been increased interest in construction problems presented by karst topography. Twenty-five years ago, karst areas were by-passed for development. Today, the high cost of land and population pressures are requiring utilization of karst areas. Areas exhibiting karst features can be satisfactorily developed so that construction can proceed in a normal manner; or the areas may be left undeveloped and the underground drainage system abused by improper use causing or contributing to structural collapse, excessive erosion, and a grave threat to the stability of land development and the environment. The term "karst" is a comprehensive term applied to areas underlain by soluble rock that possess a topography formed chiefly by the dissolving of rock and the diversion of surface waters to underground routes. There are four features which contribute to the maximum development of karst. 1. A soluble rock, preferably limestone, must be present at or near the surface of the ground. Occasionally, dolomite will suffice.

Jan 1, 1970

By K. V. Raj, C. A. Berry, A. T. Weakley, A. L. Miller, P. R. Griffiths, D. A. Parks

Diesel particulate matter (DPM) has been classified as a carcinogen to humans by the International Agency for Research on Cancer. DPM exposure is therefore regulated by the U.S. Mine Safety and Health Administration (MSHA). The current monitoring process takes days or weeks for exposure levels to be known, and a real-time monitoring device is needed. It is believed that infrared spectroscopy has potential for use in a real-time, field-portable device. This paper presents a method for measuring organic carbon (OC) and elemental carbon (EC) in DPM for a broad range of OC/EC ratios. 

By YUSONG MIAO, DI WU, XIANRONG YAN, YIPING ZHANG, JIE LIN, KEBIN LI

Rock fragmentation has been a concern in hard-rock mining for the mining industry. Rock fragmentation distribution is an important index to measure the blasting effect. It not only affects the cost of drilling and blasting, but also affects the efficiency of subsequent operations, such as loading, transportation and secondary crushing.

By S. W. Nicholson, L. G. Woodruff, K. J. Schulz, W. E. Cannon

The 1.1 Ga Midcontinent rift of North America has many similarities to the geology of the Voisey's Bay region in Labrador and the geology of the Noril'sk region in Siberia. These similarities include the hosting of large volumes of sulfur- undersaturated and trace-element-enriched basalt, having igneous centers characterized by crustal contamination, being characterized by metal depletions in some mafic units (an indication of prior sulfide segregation) and having known occurrences of Ni-Cu sulfide mineralization. These similarities along with new geophysical data and refined models for Ni-Cu sulfide deposits suggest that the Midcontinent rift probably contains undiscovered Cu-Ni [±] PGE sulfide deposits, some of which could be the size and grade of a Voisey's Bay or Noril'sk deposit. In particular, intrusions and related feeder systems that occur in northern Michigan and Wisconsin, as well as to the southwest along the rift margin, deserve serious examination.

Jan 1, 1999

By L. Diestelow

Evaporation and crystallization processes are used extensively in the mining industry to provide many pro-ducts. In the case of solution mining evaporators are used to concentrate, or to concentrate and crystallize the raw materials being mined. In the case of underground, or strip mining dissolving and crystallization are used in many processes in order to purify the ore to saleable materials. Presently evaporators and crystallizers are being used in the production of sodium chloride, potassium chloride, sodium carbonate, sodium sulfate, lithium chemicals, aluminum, and many others. The evaporator is a device designed to remove water or solvent from a solution. In an evaporator the energy released by steam condensing on one side of the heat transfer surface is transferred to the product solution on the other side of the heat transfer surface. As long as the boiling temperature of the product liquor is below the condensing temperature of the steam, the product solution will absorb heat. This heat absorption causes vaporization of the water (solvent) in the product solution resulting in concentration of the product. The simplest evaporator is the single effect evaporator. If we assume the feed introduced into the single effect evaporator is at its boiling point, ignore radiation losses, and assume the steam into the heat exchanger is dry and saturated, then the heat transferred will correspond to the latent heat of vaporization. Therefore, one kilogram of condensing steam will produce one kilogram of evaporation. Economies in energy usage compared to the single effect evaporator can be made by using multiple effect evaporators, or vapor recompression evaporators.

Jan 1, 1993

By Meredith Scaggs, Emily Sarver, Lucas Rojas Mendoza

"Early on Jan. 9, 2014, approximately 37,800 L (10,000 gal) of crude 4-methylcyclohexanemethanol (MCHM) leaked from a storage tank sitting on the bank of the Elk River near Charleston, WV (WVDEP, 2014; CSB, 2014). MCHM is a chemical commonly used in preparation of fine coal and is considered nonhazardous in terms of transportation, storage regulations and also toxicity (CDC, 2014a). Freedom Industries Inc., a producer and vendor of specialty chemical products, had acquired the storage facility from Etowah River Terminal, LLC just a few weeks prior in December 2013 (WVDEP, 2014; Freedom, 2005). The direct cause of the spill was ultimately determined to be two small holes in the base of the 76-year-old tank, which were created due to corrosion damage (Bauerlein and McWhirter, 2014).The spill site was located a little more than 1.6 km (1 mile) upstream from the intake of a municipal water treatment facility operated by West Virginia American Water (WVAW), which serves a population of 300,000 across nine counties in central West Virginia (CDC, 2014a). In a matter of hours, the leaked MCHM made its way through the treatment facility and into the water of nearby homes and businesses, where its strong smell was noticed almost immediately. On the evening of the spill, WVAW concluded that its conventional treatment processes, which include carbon filters to remove a variety of contaminants from water, were not capable of fully removing the MCHM and a "Do Not Use" order was issued for all customers (WVAW, 2014a).With little information readily available regarding the potential human health effects of MCHM, the U.S. Centers for Disease Control and Prevention (CDC) quickly issued an advisory ruling that set a maximum screening level of 1 ppm for safe drinking water (CDC, 2014a). Based on this recommendation, the "Do Not Use" order remained in effect for a total of eight days, until Jan. 17, when the WVAW distribution water was confirmed to have MCHM concentrations below the approved level (WVAW, 2014a). However, due to the pungent odor of the chemical, its presence was still recognizable in the WVAW facility and in consumers’ tap water after the order was lifted (Manuel, 2014). Recent studies have shown that the chemical can be detected in water at sub-ppb concentrations, a fact that undoubtedly added to growing public concern (Rosen et al., 2014; Gallagher et al., 2014). In response to numerous complaints and demands, WVAW continued flushing the treatment facility and pipes until Feb. 25 when MCHM levels were measured below 2 ppb (WVAW, 2014b), and eventually replaced the affected filter media (WVAW, 2014c)."

Jan 1, 2014

By Amy McBrayer, Andrea Brickey

The paper discusses the mine planning methods used in the Powder River Basin (PRB), highlighting the differences from open-pit metal mines. It emphasizes the need for agile mine operations due to changing commodity markets and the challenges faced by the coal industry, such as volatile prices and reduced engineering manpower. The study includes a survey of mine engineers to document current practices and identify potential improvements.

Sep 1, 2023

By Louis M. Schlesinger, Joel F. Hutwelker

A pilot plant was constructed to attrition scrub and deslime North Carolina phosphate ore. A 15.2 cm (6 in.) diameter pilot-scale Linatex Hydrosizer was used for desliming. Four tests were run at a throughput of 2.9 t/hr/m2 (0.30 ton/hr/f t2) and a teeter bed density of 1.12-1.13 g/cm3. The teeter water flow rate was varied to create an upflow velocity ranging from 0.25-0.47 cm/s. (This latter value is equal to the terminal settling velocity of a 200 mesh (74 micron) particle having a density of 2.7 g/cm3.) The recovery of +200 mesh oversize to the sizer underflow was 95%-96%, regardless of the teeter flow rate. The recovery of -200 mesh undersize to the sizer overflow increased from about 90% at 0.25 cm/sec to 100% at 0.47 cm/sec. A metallurgical balance that was conducted for one of the tests showed that less than 2% of the phosphatic value was lost to the overflow. A fifth test was run using an upflow velocity of 0.47 cm/sec; however, the teeter bed density was maintained at 1.05 cm/sec. This change had the effect of reducing the cut point (d50), while maintaining complete slime removal.

Jan 1, 1993

By Biswajit Samanta, Pranjal Pathak

A multimine mineral value chain (MVC) consists of multiple mines in the upstream supplying raw materials to multiple destinations in the downstream. The short-term mine production scheduling problem of a multimine MVC aims to determine the optimal extraction sequence and destination allocation of blocks from all the mines collaboratively to meet the quality and quantity requirements of all the processing plants in each period, subject to all relevant technical and operational constraints of the mining system. It is carried out at shorter scales of days/weeks/months under the purview of long-term production scheduling. An optimal short-term production schedule for MVC involving multiple mines that share the same infrastructure (processing units, stockpiles and waste dumps) requires coordination across the network of mines. Optimizing the short-term production schedules independently at each mine fails to capture the benefit of collaboratively generating schedules for all the mines, resulting in suboptimal schedules. Additionally, in short-term production scheduling, the operations are modeled in greater detail with additional decision variables and constraints to model the more complex multimine MVC situations. This makes the large-scale instances of the problem computationally intractable for standard mixed-integer programming (MIP) solvers. This work presents a customized genetic algorithm (GA)-based heuristic approach to obtain near-optimal solutions to the industrial-scale instances of the short-term production scheduling problem of multimine MVC within a reasonable computation time.

Oct 1, 2022

By Dan Plazak

The authors are to be congratulated for presenting a simple and practical tool for quick estimates of ground water flow rates. At the risk of detracting from the simplicity of the method, I would like to suggest a slight refinement to the equation as presented. As the authors noted, the Jacob-Lohman equation (1952) assumes confined-aquifer conditions. To use confined-aquifer equations in water-table aquifers, Jacob (1963) presented a correction to convert water-table aquifer drawdowns [ ] to equivalent confinedaquifer drawdowns [ ]:

Jan 1, 1994

By David J. Hatem, K. Bhattarai

Effective risk management in major subsurface projects involves ways to mitigate adverse impacts to final design and construction approaches due to changed subsurface conditions. An Early Contractor Involvement (ECI) collaborated with Observational Method will be an effective contractual tool to address risk developed due to encountering differing site conditions. Observational Method (OM) can further be supported with artificial intelligence (AI) technologies with automated data-driven decision-making features in risk mitigation and implementation of proper design and construction approaches. This paper presents collaborative applications of ECI, OM, machine learning, and risk baselining in risk management and productivity enhancement in tunneling projects.

Jun 23, 2024

By AKIHIRO YOSHIMURA, HIDEKAZU KATO, KOTA TAKATORI, YASUNARI MATSUNO

Chalcopyrite (CuFeS2) is the most refractory copper mineral when treated in conventional sulfate media leaching systems. This study is the first to examine the use of a dimethyl sulfoxide (CH3SOCH3), or DMSO, solution containing copper chloride (CuCl2) in the leaching of chalcopyrite. The DMSO solution containing CuCl2 could selectively dissolve the valuable metals of copper (Cu) and gold (Au) from chalcopyrite while leaving minerals with little economic value, such as pyrite (FeS2), and the penalty element arsenic (As) in the residues. Leaching chalcopyrite using a DMSO solution that contains CuCl2 offers a number of advantages, including eco-friendliness and easy operation.

By Dion Weatherley, Raúl Castro, RENE GOMEZ, Pablo Cid

The study examines the impact of different drawbell geometries on hang-ups during ore extraction in underground mining. Using the discrete element method, the research compares three drawbell geometries: drawer, circular, and El Teniente. The findings indicate that the El Teniente geometry experienced more hang-up events, while the circular geometry had fewer.

Sep 1, 2023

By Kristian E. Waters, Hao Ma, Haibei Wang

Heavy metal ions exist in waste effluents including mining tailings, manufacturing discharges, and smelting and metal plating process wastes. Various methods are available to treat industrial effluents containing high levels of metal ions, but when confronted with wastewater that has low metal ion concentration below 500 mg/L, most techniques suffer from low removal or separation efficiency as well as high operating cost. ELM-based techniques can be used to solve these problems.

Apr 1, 2023

By Kevin Erwina, Rajiv Chandramohana, Connor Meinkea

This paper explores prevalent operational challenges encountered globally in SAG mills, including suboptimal throughput, liner wear, excessive energy consumption, and SAG mill load stability. The paper delves into the root causes behind these issues, such as ore variability, poor operating strategy, or inadequate process control. Drawing on industry experience and case studies, the paper highlights the significance of addressing these challenges to enhance overall mill performance and efficiency. It underscores the necessity of tailored strategies, encompassing improved monitoring, optimized liner designs, and refined control techniques to mitigate these challenges and promote sustainable SAG mill operation.

Feb 1, 2024

By Jerry C. Tien

The rare earth elements (REEs) are a group of 17 chemical (metallic) elements. REEs are used widely in high-technology, clean-energy products as well as weapon systems. China's dominant position as a producer of over 95% of the world REEs output and the world's increasing reliance on REE products have highlighted concerns about the future availability of rare earths in recent years. This paper briefly reviews the REEs world reserves, production, consumption, the impact of our heavy reliance on REEs products and China's changing policies on REE export on world supply chain.

Jan 1, 2013

By Armando Correa de Araujo

Cationic flotation of quartz is currently utilized for the concentration of iron ores and for the cleaning of phosphate concentrates. The present work deals with depression of quartz in the presence of aluminum ions during cationic flotation. It was established-that aluminum ions depress the flotation of quartz with an amine, especially under neutral and very slightly alkaline conditions. Studies of adsorption of Al ions on the quartz surface as a function of pH correlated with depression of this mineral with an amine as collector. The presence of Al ions also enhanced the depressant action of corn starch on quartz The sodium salt of ethylenediaminotetra-acetic(EDTA) was found to be an effective complexing agent to supress the depression caused by aluminum ions.

Jan 1, 1984

By A. A. El-Midany, R. M. Farag, A. M. Salem, S. E. El-Mofty

Bentonite is one of the main players in the stability of drilling mud. Its particle size and particle size distribution significantly affect drilling mud’s rheological properties. Although the Specifications for Drilling Fluids Materials report on Oil Companies Material Association (OCMA)-grade bentonite states that the API recommended powder having 2.5 percent mass fraction as the maximum value of residue of diameter greater than 75 μm, there is no other information on the specific size distribution for API bentonite. It was found that API bentonite has a specific size distribution with specific mixing weights. It is important to investigate why that mixture represents the optimum properties of drilling mud and how each individual size fraction has a specific function in the mixture. To clarify the effect of individual size as well as the collective effect of the size distribution, API bentonite was classified into different size fractions, with each tested separately for controlling properties such as filtration loss, plastic viscosity, gel strength, cake thickness and packing density.

By H. H. Hayden

The accident repeater-40 you have one at your mine? Unless your company is vastly different from most coal companies, you will find that a small percentage (11-12%) of your employees will have a large percentage (47-50%) of your accidents. When you find out that this is a fact, what do you do? First, you establish a set of guidelines that can be used in identifying the ?accident repeater?. Next, you determine the type of action necessary to improve work habits and safety performance of the accident repeater. With these two steps in mind, objectives are developed for an ?accident repeater? program.

Jan 1, 1984

By Paul D. Tomlingson

An effective maintenance program ensures the adequate availability of production equipment. In turn, this availability enables production to maximize utilization and successfully meet production targets. An overall production strategy is necessary to draw all departments toward this common effort. Only then will production targets be met. From the maintenance view this means that production must comply with PM and repair schedules. Purchasing must supply parts and materials on time. Mine engineering must not overwhelm maintenance with non-vital construction. Accounting must provide correct, timely cost information - - etc. This strategy - - its content, effectiveness and enforcement is the responsibility of the mine manager . . . his alone. This paper describes a successful approach to maintenance within this strategy.

Jan 1, 1979